Some new wisdom from experience.....C8 Z06 with Cup 2 tires.

[Michael J.]

In case anyone out there has a C8 Z06 with the Michelin PS Cup 2 tires, beware of quick and early wear and low mileage wear out, even in highway only driving. I went on a trip to Colorado to drive the high mountain twisty, turny, switchback laden roads like the Million Dollar Highway. I had about 5500 miles (in 6 months, all highway driving) on the tires, and looked them over before the trip. It was about 2/32nds on the wear bar, but I thought that would be OK for this last trip. Wrong, at 6400 miles I had a loud blow-out on the right rear. The indicators on the dash light up, zero pressure on that tire. I was 20 miles from home and since these are run flat tires, drove about 45 MPH the last leg home. The pictures show the wear down through the cord, so beware, these tires can fail quickly, even over a few hundred miles. But I was very lucky to be so close to home. 508323023_10224762460923849_2478574716068924051_n.jpg 505747141_10224765060828845_7208978353348000489_n.jpg

[Joseph S.]

Good to know. Thanks Mike!

[Leif A.]

That completely sucks, Michael. Glad to hear you and the car are safe and sound. They sound like F1, soft compound tires

[Michael J.]

Thanks Leif, yes we were lucky. In checking around, I had some show me their Cup 2s worn-down to the cord in 1400 miles or less with lots of track time. They were amazed I got 6400 miles. So I guess they are about the same as racing tires in terms of soft rubber and rapid wear. I do wish Chevrolet would have put a warning leaflet in the glove box materials about how poor they are for wear, and give you a better idea of how quickly they go bad.

[Duke W.]

According to specs I've read the rear Michelin Pilot Sport Cup 2 R ZP tires are 345/25R21. New tread depth is 5/32" (half of typical summer high performance tires) and the wear rating is 140, which doesn't quite make them DOT legal racing tires (100 or below IMO), but pretty close.

So if you had 2/32" tread depth left, they wore 3/32 in 5500 miles, which is a little over 1800 miles per 32nd, so with normal highway driving you could have gotten about 9K miles if you wore them to the cord, however, you might only get one weekend out of a set of those tires on a big track, say about 300 miles over a two-day event with 4 20 minute hot lap sessions per day. I think the wear rating is optimistic.

Sporty driving on canyon and mountain roads can increase the wear rate 2-5 times depending on how hard you push, and a mid or rear engine car will go through two sets of rears for every set of fronts in normal driving, and probably even more in track events or with a lot of sporty driving on twisty roads.

I recall from back in the early nineties Honda NSX owners filed a class action lawsuit against Honda because they only got 10K miles out of the rear tires. I was acquainted with a Honda America executive at the time, and I suggested to him that Honda buy back the cars and recommend the owners use the funds to buy a Mercedes 300 SD.

BTW, I noticed on tirerack.com that those tires are $776 each... and I thought Avons for C2s are pricey!

Duke

[Terry M.]

Mike I shared some of my experiences with you on the NCRS Facebook page, but I'll amplify here. Sorry this is so long, but it is my heritage.

When I began driving my 2008 Z06 I smelled burning rubber at fuel stops after driving on the highway. At first I didn't believe it was my "new" car. Once I realized it was my Corvette I had a lot of people, including some Chevrolet Engineers, try to solve the problem. I replaced the first two sets of Goodyears as they wore out. The third set of Goodyears had a highway failure similar to yours at a far less convenient location. I am embarrassed to admit that at that point I finally realized the camber was set negative for track driving. A highway alignment, eliminating that negative camber among other settings, solved all my wear problems and a switch to Michelins solved an annoying noise issue. One of the engineers told me that the cars were built with "net build." I am a cynic, so I will save you my translation of the meaning of that term. You may reach your own conclusions.

When I got my 2023 Z06 I had a road alignment done in the first 500 miles. The left front was red on the alignment read-out. The 4-wheel alignment took over four hours, but I have confidence in the craftsman that did that job. He did complain about having to remove all the under-body panels. I compensated him well for his efforts. I want to maintain his friendship and access to his skills.

I don't know if they still use "net build," and I no longer have the engineering connections I had 15 years ago so I can't find out, (not that it would matter much anyway) but I highly recommend a good 4-wheel Highway or road alignment shortly after taking delivery of any new Corvette. I got C8 road alignment settings from the folks at Ron Fellows as part of their school, but they are also available with an on line search .

Happy many miles of smiles.

[Michael J.]

Thanks Duke and Terry, now you see, if I had asked you guys before I took delivery of this car, I would have not been surprised and much wiser........

[Lawrence S.]

For what it's worth, I have never changed the alignment on my C7 Z06 prior to tracking the car at VIR. In the owners manual the specs are listed to "track" align the car. I now drive the car more frequently on the road than I use to with casual track time.
My car came with Michelin Super Sport tires (non Z07) car. Where the Z07 cars came with the Pilot Cup 2 tires which I now run for both track and street. They are great for the track but crummy for the street because of what you guys are mentioning, fast wear.

[Duke W.]

One of the engineers told me that the cars were built with "net build." I am a cynic, so I will save you my translation of the meaning of that term. You may reach your own conclusions.

"Net build" usually refers to "no adjustment". For example, my '91 MR2 has no front or rear camber adjustment. The nominal spec is negative one degree, front and negative 1.5 degree rear, and it's spot on. There actually is a way to adjust camber... so called "crash bolts"... bolts with offset shanks to bring the camber back into spec in the event of going out of spec due to accident damage.

I thought that Chevrolet built the highest performing C7/8 Corvettes with "street alignment", but also recommend "track alignment" settings for those who want to track their cars, but warn that track settings will cause more rapid tire wear in normal road use.

Mid or rear engine cars are tough to get right, but when they are right they're fantastic! When new the MR2 proved to be a handful and it almost snap-spun on me twice in the first couple of weeks on trailing throttle. It was like an early 911. What had I got myself into? One thing that few guys don't pay attention to - actually virtually nobody - is tire load capacity, which is basically a function of contained air volume. As a general rule, the lower the vertical load on a tire the greater the lateral g it can make.

The MR2 static weight distribution is 43.5/56.5 percent and given that the fuel tank is in the center tunnel and the occupants sit near the unloaded cg, the cg doesn't change materially with fuel or people load. However, the OE tire load capacity was more like 48/52 percent. So in the first two weeks I ordered a set of 225/60HR-14 Bridgestone RE 71 tires to replace the 205/60s on the OE 7" wide wheels, and that solved the oversteer problem. The larger rear tires added 200 pounds more load capacity at each rear corner and brought tire load capacity distribution right into line with weight distribution. I also reduced rear toe-in from the factory spec of 5 mm to 1.5 mm (front is 1 mm). It certainly didn't help tire wear or rolling resistance to be dragging the rear tires down the road sideways, and the one inch larger diameter brought the wildly optimistic speedometer (5 percent high) to near dead-on true.

I also bought a set of OE take-off wheels and mounted Yokohama A008 DOT legal racing tires. At the original 1.2 mile Streets of Willow Springs course I ran time trials events with the local track time focused Porsche Owners' Club and gave the Porsches fits. A guy once asked me how much boost I was running and I replied "zero". it's not a Turbo model... just has the 2.2L 130 HP Camry engine, but it's real torquey and perfect for a tight course like the original "Streets". With the RE 71s (later replaced with Yokohama A 509) I can induce oversteer on a tight corner in second gear, but it's very predictable and controllable. With the A008s, it's dead neutral, which helps keep one out of the weeds on a track.

I recall when Car and Driver tested a '91 MR2 Turbo (200 HP, same tire sizes but V-rated) they said the rear tires were the most "overworked" of any car they had ever tested!

I keep detailed records of tire wear and the "street" tires (RE 71, A509) are good for about 30K/15K F/R miles of road driving, and the A008s are about 20K/10K of normal road use, but less depending on how much track time. Being as how the car has just over 50K miles and I'm now only accumulating less than 500 miles per year and have a stash of new 509s and 008s, I'm not worried about running out of tires in my lifetime.

BTW, I don't think Micheal's Z06 has excessive negative rear camber. The corded area appears to be just slightly inboard of the circumferential centerline, which is exactly where the MR2 wear is greatest on the rear tires, but it's no more than 1/32" more than the outside shoulder. The greatest wear on the fronts is on both shoulders.

Duke

[Michael J.]

I have had one owner comment on how the recommended cold tire pressure for the Z06 Z07 car, at 34-35 psi, is too high and intended to make sure the hydroplaning that is common for the Cup 2 tires is lessened. That overinflation bows the tire so that the center wears faster than the edges, and this why mine is worn through in the center, but still has above the wear bar tread on the edges. I think I will reset that cold tire pressure to 30 when I get the AS replacements.

[Terry M.]

I have had one owner comment on how the recommended cold tire pressure for the Z06 Z07 car, at 34-35 psi, is too high and intended to make sure the hydroplaning that is common for the Cup 2 tires is lessened. That overinflation bows the tire so that the center wears faster than the edges, and this why mine is worn through in the center, but still has above the wear bar tread on the edges. I think I will reset that cold tire pressure to 30 when I get the AS replacements.

Ny non-Z07 door jam label calls for 30 psi at 70*F. The owner's manual calls for 38 psi Front and 42 psi Rear for "high-speed" driving for the Z06 tire sizes. They define "high-speed" as 100 mph or higher travel.

After this discussion I am going to pay a lot more attention to tire wear of my C8.

[Michael J.]

After this discussion I am going to pay a lot more attention to tire wear of my C8.

Good idea, I wish I had rather than just looking at the wear bars I could see easily. I have a 2022 Shelby GT500 with the same Cup 2 tires. It has 8000 miles on it and what looks like at least 4/32nds and not down to the wear bars. But I think I will soon replace those tires too, just to be safe and confident on a longer trip they aren't going to wear through to the cord.

[Bill M.]

Mike
Pretty discouraging tire news !! Since I am using my Z06 as a daily driver what will the best tire be to use as replacements ? Or do I stay with the Michelin's ?
bill

[Michael J.]

Mike
Pretty discouraging tire news !! Since I am using my Z06 as a daily driver what will the best tire be to use as replacements ? Or do I stay with the Michelin's ?
bill

I ordered a set of Michelin Pilot Sport 4+ ZP All Season. I think they will give me more miles than the Cup 2 R by far, and be better for cold/wet traction situations than Cup 2s or the Pilot Sport 4S. I didn't see any other brands in the size for the 2025 Z06 Z07 optioned.

[Bill M.]

I drove my Z06 home from Ciocca Chevrolet on December 20th. Raining in New Jersey and snowing on the NY Taconic parkway. The tires handled great. Thanks for the info.